Molecular-dynamics study of electronic sputtering of large organic molecules

In order to describe electronic sputtering of large organic molecules from a solid as a result of the passage of a fast heavy ion, a molecular-dynamics calculation was carried out. A modified Lennard-Jones potential is used to describe the intermolecular interaction. When the ion passes through the organic solid, the excited molecules near the ion track are assumed to expand due to the energy deposited so that the forces between them become repulsive. Both excited and unexcited molecules are ejected due to the compression wave emitted from the track. Sputtering yields as well as angular and velocity distributions of ejected molecules were studied as functions of energy input, angle of incidence, and material cohesive energy. The results are consistent with a number of experimental observations and our analytical model.